共查询到18条相似文献,搜索用时 234 毫秒
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提出了一种基于业务负载选择的光分组交换(OPS)网络的光缓存结构,根据业务负载大小灵活选择缓存方式。输出缓存光纤延迟线(FDL)采用分段式共享机制配置,输出/反馈共享缓存模块采用简并式配置,以提高有限数目FDL的利用率。分析和仿真表明,这种可选择的缓存结构可以有效降低丢包率和OPS节点需求的FDL数目。 相似文献
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最大缓存时间限制、时延粒度限制、光分组长度限制3大限制因素,对传统光缓存器的前馈型和反馈型两种结构进行了分析。分析表明,影响光缓存器性能的3大限制因素在两种结构中的相互制约关系限制了光缓存器性能的进一步提高。在此基础上提出的一种自适应弹性环光缓存器(E-FLOB)结合了两种传统结构的优势,并分离了3大限制因素间的相互制约关系。结构分析显示,E-FLOB在缓存级数为16时可减少反馈型光缓存器噪声积累约3个数量级。网络性能仿真表明,弹性环结构比前馈型结构使用更少的缓存级数,获得比两种传统结构更低的分组丢失率。 相似文献
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研究了FDL和有限长波长转换器(LRWC)相结合的方法来解决异步变长的分组交换网中的冲突问题,对这种冲突解决方案建立了数学模型并进行了理论分析,提出了一个用于修正最佳延迟单元的公式,即在负载较大的情况下,我们要求延迟单元较小,这样可显著的降低在此交换网中的分组丢失率;对系统丢包率与负载、FDL数目和最佳延迟单元的关系进行了研究和讨论,结果表明:在同样的输入负载情况下,有限长波长转换器(LRWC)的引入可以降低缓存的数量;对延迟单元的修正可以大大降低丢包率,同时系统的性能较之单独使用FDL时有较大的改善。 相似文献
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光分组交换网络中光纤延迟线缓存技术 总被引:2,自引:2,他引:0
光分组交换网是全光网络发展的必然趋势.然而,光分组交换网络发展的瓶颈是光缓存技术.目前,在光域比较现实的还是采用光纤延迟线(FDL)作光缓存.重点研究了光纤延迟线光缓存技术,对FDL光缓存技术进行了深入的分析和归纳,并对每一种光纤延迟线光缓存调度策略的优缺点都进行了细致的分析.最后指出了光纤延迟线光缓存技术的未来研究重点和发展方向. 相似文献
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光分组在核心节点处的冲突解决问题是实现全光 组播分组交换的关键。本文提出了一种新型的解决光组播冲突的节 点结构,用于冲突解决的部分包括输出共享的网络编码模块和光纤延迟线(FDL)环 形反馈共享缓存(FDL-LSFB)模块。网络编码 模块将异或网络编码作为冲突解决方式,利用全光异或门将冲突组播进行网络编码并且改变 编码后分组波长,从而避免波长 冲突。而FDL-LSFB模块由子交换矩阵和FDL缓存组连接成环状,且冲突组 播可从任意子交换矩阵进出缓存模块, 使用少数的FDL可以提供大容量的光缓存、提高FDL利用率。针对FDL-LSFB模块冲突组播调 度问题,为减小缓存时延,设计了最小缓存长度级联控制算法(MLCBST),进而提出冲突光 组播的总调度策略。仿真结果表明,本文提出的组播节点结构和调度策略在降低丢包率(PLP)和减小缓存时延方面具有明显的效果。 相似文献
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Choo Peng Tan Gerardo Castañón Su Fong Chien Ah Heng You Andy Lock Yen Low 《Photonic Network Communications》2006,12(3):257-268
This paper studies several buffering strategies for optical packet switching (OPS) under limited packet sorting. Three schemes, which are able to sort newly arrived packets based on packet’s length as well as capability of finding the minimum buffer occupancy, are analyzed and compared. Results show that all three proposed schemes could improve OPS performance considerably in terms of probability of packet loss (PPL) and probability of information loss (PIL). In addition, the simulation results show that not all the newly arrived packets need to be sorted in order to obtain minimum packet loss probability. Since the amount of packets and thus the packet processing time is significant in OPS, it is possible that not all the packets can be processed using one of the buffering strategies. An important finding of this paper is that if only 10% of the packets are sorted, the PPL is comparable to the minimum packet loss value obtained when 100% of the packets are sorted. 相似文献
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Scheduling Algorithms for a Slotted Packet Switch with either Fixed or Variable Length Packets 总被引:3,自引:2,他引:1
Callegati F. Cerroni W. Corazza G. Develder C. Pickavet M. Demeester P. 《Photonic Network Communications》2004,8(2):163-176
We address the problem of congestion resolution in optical packet switching (OPS). We consider a fairly generic all-optical packet switch architecture with a feedback optical buffer constituted of fiber delay lines (FDL). Two alternatives of switching granularity are addressed for a switch operating in a slotted transfer mode: switching at the slot level (i.e., fixed length packets of a single slot) or at the burst level (variable length packets that are integer multiples of the slot length). For both cases, we show that in spite of the limited queuing resources, acceptable performance in terms of packet loss can be achieved for reasonable hardware resources with an appropriate design of the time/wavelength scheduling algorithms. Depending on the switching units (slots or bursts), an adapted scheduling algorithm needs to be deployed to exploit the bandwidth and buffer resources most efficiently. 相似文献
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An optical router with multistage distributed management features for the asynchronous optical packet switching (OPS) network
is presented, which can improve switching capacity and all-optical scalability. A compact recycling-fiber-delay-line (Rec-FDL)
based collision resolution mechanism is proposed to resolve the contentions for asynchronous and variable length optical packets.
The analysis models of stabilities, packet loss rates (PLR) and average packet waiting latencies (PWL) for the router are
developed based on the timer based optical packet assembly algorithm. The simulation shows that PLR and PWL for a 400-byte
optical packet transmitted in the 32 wavelengths dense wavelength division multiplexing (DWDM) system equal to 3.48 × 10−4 and 0.072 ns, respectively. The non-blocking switching can be realized for the packets with lengths less than the buffer
granularity of the Rec-FDL, and the optimized performance for the proposed router can be obtained through properly selecting
of the system parameters. 相似文献
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ABSTRACTIn recent years, Wireless Sensor Networks (WSNs) are widely placed in real-time monitoring systems like environmental, structural, patient monitoring, etc. The major criterion for WSN includes energy efficiency and network lifetime. Scheduling is used as a large number of data packets focus on the same queue at the same time. Only limited data scheduling schemes have been implemented in WSN to enhance the performance. The existing First Come First Serve (FCFS) and Dynamic Multilevel Priority (DMP) have some technical challenges like delay, packet drop and high energy consumption due to starvation and deadlock. In this paper, we proposed a new algorithm to optimise and rank the incoming data packets based on multi-attributes decision-making methodology named as Packet Rank Based Data Scheduling (PRBDS), the algorithm selects packet priority, deadline, and size as the metrics to rank the incoming data packets. A simulation result shows when compared with existing scheduling, PRBDS not only provides less energy consumption, also significantly reduces the packet drop and increases the lifetime. Thus, the proposed algorithm is most suitable for real-time monitoring system since it combines data ranking method with scheduling algorithm to create accurate and reliable results to evaluate the incoming data packets. 相似文献
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In current code division multiple access (CDMA) based wireless systems, a base station (BS) schedules packets independently of its neighbours, which may lead to resource wastage and the degradation of the system's performance. In wireless networks, in order to achieve an efficient packet scheduling, there are two conflicting performance metrics that have to be optimized: throughput and fairness. Their maximization is a key goal, particularly in next-generation wireless networks. This paper proposes joint packet scheduling and BS assignment schemes for a cluster of interdependent neighbouring BSs in CDMA-based wireless networks, in order to enhance the system performance through dynamic load balancing. The proposed schemes are based on sector subdivision in terms of average required resource per mobile station and utility function approach. The fairness is achieved by minimizing the variance of the delay for the remaining head-of-queue packets. Inter-cell and intra-cell interferences from scheduled packets are also minimized in order to increase the system capacity and performance. The simulation results show that our proposed schemes perform better than existing schemes available in the open literature. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Kazumi Kumazoe Kenji Kawahara Tetsuya Takine Yuji Oie 《International Journal of Communication Systems》1997,10(4):181-192
In asynchronous transfer mode (ATM) networks, when cells are lost due to congestion, packets containing the lost cells should be retransmitted in the transport layer, which manages the end-to-end communication. The probability that a packet contains at least one lost cell depends on the packet length. It is thus very likely that the performance of the end-to-end communication is influenced by the packet length. In this paper, we analyse packet loss probability and the achievable maximum throughput when a block of data is divided into packets of fixed size and the lost packets are retransmitted based on the selective repeat automatic repeat request (ARQ). Through this analysis, we examine the effect of packet length and peak cell transmission rate on the performance measures mentioned above. © 1997 John Wiley & Sons, Ltd. 相似文献